Nervous system Flashcards
Describe synaptic transmission
- An action potential travels down the presynaptic neuron until it reaches the synaptic end bulb.
- Then because of depolarisation the Ca2+ channels open.
- The influx of Ca2+ ions flowing into the membrane activates the vesicles containing neurotransmitters.
- The vesicles fuse with the membrane and undergoes exocytosis releasing neurotransmitters into the synaptic cleft.
- Neurotransmitters diffuse across the cleft and bind to the neurotransmitter receptor located on the post- synaptic neuron.
- Binding of receptor causes receptor molecules to activate-> causing na+ ligated channels to open causing an action potential in the post-synaptic neuron.
7.Neurotransmitter molecules eventually break loose from the receptors and drift away. - The neurotransmitter is deactivated by an enzyme and is reabsorbed back into the pre-synaptic neuron to be reused.
Outline the parts of the Cerebrum and their functions
Frontal Lobe, parietal Lobe, Occupital Lobe, temporal Lobe
Frontal lobe-> responsible for cognitive thinking, critical thinking, language,
Parietal Lobe-> responsible for sensory input contains sensory association area , ( temperature, taste, etc)
Occupita Lobe-> responsible for eyesight.
temporal lobe-> responsible for hearing, and smell.
Describe the difference between unmyelinated transport and myelinated
If unmyelineated the action potential undergoes continous conduction. and it travels along the whole axon. Action otential occurs at every adjacent section of the membrane. The speed of a unmyelinated neuron is 2m/s
If the neuron is myelinated the actionpotential undergoes through saltatory conduction. Action potential only occurs at the nodes of ranvier. As ions only flow in regions where myelin not present the pseed is 140m/s
how does neurontoxin cause paralysis of muscles
Neurotoxins inhibit neuron control over ion concentrations across the cell membrane, or communication between neurons across a synapse. Neurotoxins inhibit the opening of the Na channels causing the depress of action potential therefore causes the patient to be paralyzed.
Describe the subheadings of the efferent division
In autonomic Division Impulse is sent to heart and involuntary muscles whilst somatic sends impulse directly to the skeletal muscles ( voluntary). Autonomic is divided into sympathetic division and parasympathetic division. The sympathetic division is your fight or flight reaction whilsts parasympathetic i rest or digest. Afferent division carries impulses from body to the CNS whilst efferent division carries impulses from CNS to the body.
Somatic is divided into visceral sensory neuron and somatic sensory neuron. Their roles is to send impulses from skin muscles, organs. The effect on target organ for autonomic is either excitation or inhibitation and Somatic is always excitation. Autonomic is involuntary whilst Somatic is usually voluntary. Neurotransmitter present in somatic is only acetylcholine whilst in autonomic it is both acetylcholine and noradrenaline
How does cell therapy treat alziemers?
Stem cells can differentiate into various types of cells, including brain cells, potentially replacing damaged cells and improving cognitive function.
Outline the pathway of the Reflex arc
· The involuntary response that occurs is a reflex, which occurs along a reflex arc, that involves the spinal cord.
· A stimulus triggers the reflex
· Receptors: detect the stimulus
· Sensory/afferent neuron: transmits the impulse from the receptors towards the central nervous system (CNS) (in this case towards the spinal cord (SC)). This enters the dorsal root/branch of the SC.
· The message is relayed to the interneuron (located in the grey matter of the spinal cord)
o There are two synapses that occurs (between the sensory neuron and interneuron, and then between the interneuron and the motor neuron)
· The impulse then sent along the motor/efferent neuron away from the SC (through the ventral root/branch) towards the effectors.
· The effectors: are parts of the body that carry out the response (in this case skeletal muscles contract to move away)
Describe the four characteristics of reflexes
Not spontaenous-> a stimulus is needed
Rapid-> only a small number of neurons are needed.
Involuntary -> occurs without conscious thought ( spine)
Stereotyped-> happens the same way every single time
Describe the action potential transmission across an axon
- The resting membrane potential originally -70Mv and both the voltage gated channels ( Na+ and K+) are both closed
- The enviroment inside is maintained by Na+/K+ pumps and K+ leakage channels.
- The pump is in the ratio of 3 Na+ in / 2 K+ out
4.because there is a concentration difference K+ ions leak more than Na+ ions - During slow depolarisation a stimulus is received by dendrite and the Na+ gated channels on neuron are stimulated to open.
- causing Na+ ions to move into the cell and the membrane potential rises
- If the stimulus is too weak depolarisation doesn’t occur
- If the stimulus is strong enough, the mp rises even more than 15 mV ( hitting -55mV)
- Threshold has been met, therefore action potential is generated
- Inside becomes more positive since K+ cannot be removed fast enough.
- Because of the increase of Na+ voltage gates, this causes an influx in Na+ ions. During Rapid Polarisation, from 30 to 40 mV, Na+ channels now close, volted gated K+ channels open to try to restore mV to resting mp. The K+ ions move out of the synapse and the neuron is now repolarised.
- The K+ channels stay open until Resting membrane potential is reached.
- Hyper polarisation occurs because repolarisation typically undershoots the resting membrane potential (-90 mV), this is because the K+ channels are slow to close.
- During this period of time, neurons cannot receive another stimulus.
- Membrane now returns to -70 mV ( because of na/K pump returning to normal.
- Refractory period is when nerve impulses cannot be carried until voltage has been restored
- Action potential will not propogate in the regions that are experiencing refractory period.
Symptoms/ description and treatment of alziemers
Reduced cognitive thinking, memory loss, language problems
Alziemers occurs when there is abnormal accumalation of proteins called tau and amyloid. Tau when built up causes tangles in the neuron and when there is a build up of amyloid it causes plaque to form. Eventually neurons lose their ability to communicate. As the neurons die the brain beings to shrink.
Stem cells can differentiate into various types of cells, including brain cells, potentially replacing damaged cells and improving cognitive function.
Outline the differences in endocrine and nervous system
the nature of the message for nervous system is electrical impulses and neurotransmitters whilst endocrine is hormonal
The transport of message for nervous system is along the membrane whilst in endocrine its the blood. The time taken for the response for nervous system is rapid whilst the endocrine is slower.
What are the 4 centers of the medulla oblongata and describe each of them
Cardiac, respirator,vasomotor, vomitting, -> heart rate, breathing, blood pressure, vommiting
Describe what is an all or none response, and why it is possible for you to detect the difference between a sheet of paper and a brick being dropped on your foot
there will either be a full response or no response a partial response is not possible.
Action potential remains the same/ nerve impulse is not more intense or weaker
1. More action potentials are created in a time frame/ increase frequency of action potentials
2.Become conscious of a greater degree of pain/ more pain detected
3. Action potential remains the same/ nerve impulse is not more intense or weaker
How is the brain protected and describe their roles and structures.
The brain is protected by the skull/cranium, Cerebrospinal fluid, Meninges.
